Presentation Title

Presenter Information

Start Date

November 2016

End Date

November 2016

Location

HUB 302-162

Type of Presentation

Poster

Abstract

This study set out to create a methodology for screening possible charge transfer organic ferroelectric materials using SPARTAN '14. Ferroelectrics are polar materials whose dipole can be switched on by the application of an electric field. Their applications are varied in technology including capacitors and data memory; however traditional inorganic materials can be toxic and brittle. Organic ferroelectric can be less toxic and flexible. The systems in this study exist as non-polar monomers and all but one exhibit a charge transfer as a dimer. This charge transfer was examined using Hartree-Fock calculations and several different basis sets in SPARTAN '14. Using three different schemes for calculating atomic charges in atoms, charge differences on individual atoms, and on the total charge of each component upon dimer formation, a clear difference was detected between a neutral dimer and several donor/acceptor pairs. Initially, tetrathiafulvelene chloranil (TTFCAN), a reported ferroelectric, was examined. SPARTAN ’14 showed a difference in charge of the components of the dimer on their own versus the crystalline structure, which is indicative of a charge transfer. Calculations were repeated using other molecules that are potentially ferroelectric along with a neutral molecule. The neutral molecule showed no difference in charge, which was expected. All other molecules studied showed significant overall orbital interaction. These interactions varied, with the most charge transfer shown in tetrathiafulvelene fluoranil (TTFFAN). This was a promising result as TTFFAN showed slightly more charge transfer than TTFCAN, a known ferroelectric. Of the three charge schemes used by SPARTAN ’14, Mulliken showed the most basis set dependence. As more sophisticated basis sets are used for calculations, we would expect to see some change in the calculated charge. Electrostatic and Natural Orbitals showed little to no basis set dependence which suggests that Mulliken is a more reliable charge scheme for these calculations.

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Methods for Studying Organoferroelectrics

HUB 302-162

This study set out to create a methodology for screening possible charge transfer organic ferroelectric materials using SPARTAN '14. Ferroelectrics are polar materials whose dipole can be switched on by the application of an electric field. Their applications are varied in technology including capacitors and data memory; however traditional inorganic materials can be toxic and brittle. Organic ferroelectric can be less toxic and flexible. The systems in this study exist as non-polar monomers and all but one exhibit a charge transfer as a dimer. This charge transfer was examined using Hartree-Fock calculations and several different basis sets in SPARTAN '14. Using three different schemes for calculating atomic charges in atoms, charge differences on individual atoms, and on the total charge of each component upon dimer formation, a clear difference was detected between a neutral dimer and several donor/acceptor pairs. Initially, tetrathiafulvelene chloranil (TTFCAN), a reported ferroelectric, was examined. SPARTAN ’14 showed a difference in charge of the components of the dimer on their own versus the crystalline structure, which is indicative of a charge transfer. Calculations were repeated using other molecules that are potentially ferroelectric along with a neutral molecule. The neutral molecule showed no difference in charge, which was expected. All other molecules studied showed significant overall orbital interaction. These interactions varied, with the most charge transfer shown in tetrathiafulvelene fluoranil (TTFFAN). This was a promising result as TTFFAN showed slightly more charge transfer than TTFCAN, a known ferroelectric. Of the three charge schemes used by SPARTAN ’14, Mulliken showed the most basis set dependence. As more sophisticated basis sets are used for calculations, we would expect to see some change in the calculated charge. Electrostatic and Natural Orbitals showed little to no basis set dependence which suggests that Mulliken is a more reliable charge scheme for these calculations.